1. Field of the Invention
The present invention relates to a method for measuring optical-phase distribution, and, more particularly, relates to a method for measuring optical-phase distribution (optical-phase-distribution measuring method) by which optical-phase distribution can be easily and economically measured at high speed and with high accuracy.
2. Description of the Related Art
The optical-phase distribution (hereafter, also called optical phase-distribution in some cases) includes information on: the wavefront shape of a light source; the refractive index distribution of a transmitting object; the surface shape of a reflecting object; and the like. It is required in many fields, for example, for design evaluation of an optical system; quality control of an optical element such as a semiconductor laser element and a lens; surface-shape measurements for noncontact nondestructive inspection, microscopic observations, and the like; and adaptive optics used for wavefront shaping and celestial observations. A quantitative measurement of the optical phase distribution is very important for engineering. Recently, measurement of a phase distribution called aberration analysis has been a necessary and indispensable technology for evaluation of an information write-and-read device using a laser, wherein the device is typified, especially, by a DVD pickup (refer to the non-patent documents 1 and 2).
For example, a method (hereinafter, called an optical-phase-distribution measuring method using an interferometer) (refer to the non-patent document 3), by which relative phase distribution of light to be measured and reference light is obtained, using an interferometer, and a method (hereinafter, called an optical-phase-distribution measuring method according to a Shack-Hartman sensor) (refer to the non-patent document 4), by which phase-gradient distribution is detected with the Shack-Hartman sensor to obtain the phase distribution, have been included so far as a method by which optical-phase distribution is measured, using hardware (that is, a special measuring device)
However, there have been a problem that the special measuring device (that is, hardware such as an interferometer, and a Shack-Hartman sensor), which has been used in the above-described conventional optical-phase-distribution measuring method, is very expensive, because the special measuring device includes a precise optical instrument, and space for installing the above special measuring device is required. There has also been a problem that efforts for measuring adjustments and measuring errors are increased when the scale of the phase distribution for light to be measured is in the level of a wavelength.